Tear-out can end with organic inner seal member



All@ 20, 1968 B. B. LIPsKE 3,397,811

TEAR-OUT CAN END WITH ORGANIC INNER SEAL MEMBER Filed April 17, 1967United States Patent O 3,397,811 TEAR-OUT CAN END WITH ORGANIC INNERSEAL MEMBER Benjamin B. Lipske, Downers Grove, Ill., assignor toNational Can Corporation, Chicago, Ill., a corporation of Delaware FiledApr. 17, 1967, Ser. No. 631,254 13 Claims. (Cl. 220--54) ABSTRACT OF THEDISCLOSURE An easy opening can end in which a scored tear-out area isjoined to a finger tab by means of a rivet which is integrally formedfrom the material comprising the can end, wherein the scored area issurrounded by a continuous, upwardly extending ridge, and wherein anarea inside the ridge is covered with an organic plastic seal memberwhich covers the entire area defined by the score line, including theportion of the end from which the rivet is formed. In the preferredembodiment, the score line is on the inside of the end, which is madefrom steel, and the entire tear-out area is in a plane slightly raisedfrom the plane of the remainder of the end. A method is described forforming the ridges, metering a given amount of plastisol or likematerial in to the area, achieving gelation of the seal member, andfurther curing it if necessary, leaving an end with a smooth interiorsurface sealed against cracks or imperfections created by scoring andriveting during the manufacturing process.

BACKGROUND OF THE INVENTION Field of the invention The field of thepresent invention is that of easy opening can ends, particularly endswhich include a scored tear-out area which is joined to an external tab,so that the user may grasp the tab and manually remove the tear-out areafrom the can end.

The preferred embodiment is one made from steel, having a score line onthe inside, a tab attached to the tear tab by a rivet, and an insidearea surrounding the tearoutportion covered with a plastisol seal. Thisinvention is also in the field of methods of manufacturing such ends,namely inverting the end, drawing or embossing a boss from which atear-out will be formed drawing a rivet from a portion of the tear-outarea, attaching a tab to the rivet, filling the embossed area with aplastic sealing material, and curing it in place in the can end.

Thus, the field of the present invention is that of easy opening canends made from tinplate or tin free steel, which are suitable for usewith beer, beverages, and other comestible products.

Description of the prior nrt Easy opening can ends made from aluminumare Well known in the can art, as are easy opening ends of tinplatedsteel which include an aluminum tear-out portion crimped in placetherein.

Easy opening ends of steel, whether tin plated or not, have beendeveloped to a certain extent, but have not found broad commercialfavor, because the scoring operation causes microscopic breaking of thetinplate coating and of the other coatings, typically organic varnish,lacquer or other plastic coatings, and when such cracks or flaws arepresent, the product reacts with the iron in the steel ends, whereby thebeer or beverage contained in such can is rendered unpalatable or untfor consumption.

When ends are made from aluminum, however, although the scoring damagesthem to some extent, the aluminum is less brittle and better able towithstand crackice ing, and furthermore, not only forms a relativelyinert oxide but, when, and to the extent, it reacts with beer, does notproduce the undesirable avor and product contamination associated withthe reaction between the iron and a beer or beverage product.

Accordingly, it has been known to protect vulnerable areas of aluminumeasy opening beer and beverage ends by a so called post repair operationconsisting of coating the end after manufacture with additionalvarnishes, waxes or the like.

Easy opening aluminum ends are described and claimed and methods formaking them are described in U.S. Patents Nos. 3,191,564, 3,198,155,3,191,797, all issued to E. C. Fraze.

Likewise, ends are known in which a separate removable foil seal memberis attached to the outside of a steel end by means of a suitableadhesive, such structures being described in Henchert et al., Patent No.3,251,515, and the Balocca Patent No. 3,302,818. These ends have manyadvantages in use, but production thereof is diiiicult, because thin tinfoil of a type used to cover the opening is not yet commerciallyavailable, and is difficult to decorate, and because machinery has notyet been completely de- /elloped for high speed handling of such thin,delicate There has been a demand for a tinplate end which would combinethe inherent advantages of steel, namely of economy, magnetic handling,capability, etc., and the reliability of aluminum units, and which couldbe made without greatly altering existing manufacturing techniques orcalling for the adoption of new techniques.

Summary of the invention In view of the shortcomings of the prior artdevices referred to above, an object of the invention is to provide anall steel easy opening can end which is compatible with beer andbeverage products.

Another object is to provide an easy opening end in which the regionsadjacent the tear-out area are covered by a cured plastisol sealingmaterial.

An additional object of the present invention is to provide a methodwhereby the cut, notched, or scored line can be impressed, cut, orformed on the inside of the end, for reasons which will be explained indetail hereinafter.

Another object of the present invention is to provide a steel easyopening can end which is acceptable for use in the beer and beverageeld, and which has the advantages of being more economical than analuminum en-d, rwhich can be handled and recovered by magnetic means,and which possesses other advantages of steel ends referred in mycopending application Ser. No. 458,932, filed May 26, 1965 now PatentNo. 3,280,939.

An additional yobject of the invention is to provide a method ofmanufacturing a can end having the advantages referred to herein, whichincludes `the steps of dispensing, forming, and curing a relativelythick plastisol seal in place on a portion of the inside of the end.

A still vfurther object is to provide a 4method in which handling -ofthe end during manufacture thereof is simplified.

The present invention overcomes the disadvantages of the prior art byproviding an al1 steel easy opening end in which the score line is onthe inside of the end, and in which a plastic seal covers the score andrivet areas, and is confined substantially thereto by ridges whichsurround the scored area, to protect the area, to serve as a guidemember for localizing the seal, to facilitate the calibration ofthickness thereof and to protect the user from cutting himself on theedges of the tear-out area.

These and other objects and advantages of the present invention,including those inherent therein, and the man- .3 ner of theirattainment, will considered in conjunction with a description of thepreferred embodiment of the invention contained in the followingspecilication vand claims, and as shown in the drawings below, in whichlike reference numerals denote corresponding parts throughout.

FIG. 1 is an isometric view showing the top portion of a can end made inaccordance with the present invention. Y v

FIG. 2 is an isometric view of the bottom portion of a can end, shown-at an intermediate state of the manufacture thereof.

FIG. 3 is a vertical sectional view of the can end shown in FIG. 1,taken along lines 3-3 thereof.

FIG. 4 is an enlarged fragmentary vertical sectional view of a portionof the end shown in FIG. 1, taken along lines 4 4 thereof.

FIGS. 5 through 9 inclusive are vertical sectional views of an end ofthe present invention, showing various steps in the manufacture thereof.

Referring now to the drawings in ygreater detail, there is shown in FIG.l a can end 20 including an outer curl 22, a countersink portion 24 anda principal end panel 26. A rivet 28 is disposed centrally of the canend 20 4and is adapted to -hold a linger tab 30 joined to a tear-outportion 32 which is defined by a score line 34 in the principal portion26 of the end 20. The score line 34 is covered by a cured plastisol seal36 (FIGS. 8 and 9), disposed on the bottom surface of the end 20.

Methods of forming the rivet 28, and methods for attachment thereto ofthe linger tab 30, are well known in the can -making art, and areillustrated, 'for example, in the Fraze Patents Nos. 3,198,155, issuedAug. 3, 1965, 3,191,564 issued June 29, 1965, 3,196,817, issued July 27,1965, and 3,191,797 issued June 29, 1965. Formation of the rivet ispartly shown and described in the Fraze Patent No. 3,191,564, in which,for example FIGS. 17, through 21 illustrate the formation of the rivet,FIG. 9 illustrates the scoring of the tear-out portion, FIGS. and 11show a typical tab adapted to be placed over the rivet, and FIGS. 26through 29 show the method of forming a rivet. The resulting jointformed between the tab and rivet is claimed in the Fraze Patent No.3,191,797, and a typical machine for performing this process andproducing this product is shown in the Fraze Patent No. 3,196,817.

Thus, the steps in manufacturing such an easy opening end are known tothose skilled in the can making and similar arts.

Although the teachings set forth in the patents just referred to areemployed currently with respect to aluminum, they may also be applied toforming steel, subject to the diiculties referred to above, and referredto further herein, which diliculties are overcome by the presentinvention. The rst steps of manufacturing an end according to thepresent invention are the same as those described in the above patents,with the exceptions specilically noted herein.

In the first embodiment of the invention, a can end is manufacturedaccording to the teachings of the patents referred to above, and,thereafter, the end is placed in the position shown in FIG. 7 hereof.Thereupon a metered mass of a liquid plastisol or like material 38 isdeposited from a nozzle 40 on to the can end 20. This may be done at thesame time that a compound lining nozzle 42 deposits sealing compound 44into the se'aming panel 46 of the end 20. Thereafter, the plastisolmaterial 38 is shaped by the die 48 into the configuration desired, anda permanent set or shape is imparted to the material 38 under theinfluence of heat supplied thereto from the die -holder 50 which isconnected to a suitable electrical current or like heating source (notshown). In practice, it has been found that when about 225 milligrams ofa plastisol material, of a type described below, is deposited and formedinto a seal with a thickness of about 0.010 to 0.020, a time of about 2seconds is suticient to impart a become more apparent when 4 .set orstate of gelation to this material when the die is operated at atemperature of about 3D0-325 The operation of the nozzles 40 and 42 iswell known in the can art, inasmuch as so called compound liningmachines of this type have been used in the can industry for many years.

After a set has been imparted to the plastisol materialY 38, forming itinto an integrally bonded s eal 36, the plastisol may be further curedin a so called Hurricane dryer or the like, of a type well known in thecan industry. A typical post cure such as this may approximate 30 to 50seconds at up to 425 F'.

A can end made according to the present invention may be made from asteel end, in view of the novel seal member, will possess good chemicalresistance to cor-rosion, and is `compatible with beer and beverageproducts, since the work damaged areas are completely covered with athin but product-impermeable seal.

When the can end is opened, the plastisol seal 36 which is adheredequally strongly to the can end and to the tear out portion 32, butwhich has relatively considerably less internal cohesive integrity, willseparate along the score line 34, and the plastisol remaining on the endin the areas of the score line 34 will serve to protect, to a certainextent, the raw ymetal edge thus formed. Thus, the likelihood of beingcut by such raw edges is diminished, as compared to `an end without sucha seal.

In another preferred embodiment of the invention, the scoring line 34defining the tear-out portion 32 is formed on the inside surface of theend 20. This method presents two additional advantages over theconstruction in which the line 34 is on the outside. First the innerseal, which is otherwise still necessary, in view of the cracking of theinside tin and organic coatings which occur when even an outside scoreline is formed, can cover the damaged area, and second, the outside areaneeds no seal. When an aluminum end is made, the outside surface isscored. This method is satisfactory since aluminum does not corrode oroxidize objectionably in air, while product contact may be harmful, butthe organic inside coatings formation to necessitate a separate interiorseal member, and a steel end is not damaged enough externally by insidescore line formation to require ia separate exterior seal. But since theinterior seal is otherwise required in the case of a steel end, placingthe score line on the inside eliminates the need for outside protectionon this more economical end.

A third embodiment of the can end of the present invention, includingthe method of making it, is shown in FIGS. 5 through 9 of the drawings.

In this method, the can end to which a countersink 24 and a curl 22 havebeen imparted, is held by known means in the inverted position shown inFIG. 5.'

Thereafter, -an embossed or recessed tear-out portion 32 is formed by asuitable die or punch. The tear-out area 32 is defined by a ridge 52which preferably totally surrounds the tear-out area 32, including theportion containing the rivet 28. The plane of the tear-out portion 32 isparallel to, but offset from, the principal end panel portion 26 of theend 20. The direction of oset is downward as shown in FIG. 6, that is,upwardly extending in position of use, for reasons further set forthherein.

`fThe next step is striking the area 32 defined by the ridge 52 with ascoring punch to form a score line 34, in a manner'known in the art, anddescribed, for example, inthe patents enumerated above.

During .the tear-out portiouand score line-forming operations, a rivet28 such as that shown in FIG. 4

may be formed, and a tab 30 attached thereto in the manner describedabove. Rivet formation and tab attachment are not discussed furtherherein, since, although these steps or elements are included in someembodiments of this invention, these elements are not novel in and ofthemselves.

FIG. 8 shows the nozzles 40, 42 depositing the plastisol material 38 andcompound liner 44 in the areas defined respectively by the ridge 52 andthe seaming panel 46'. The compound liner 44 may be deposited at anearlier stage of manufacture in a conventional manner if desired. Thisstep does not form a necessary part of the invention, but is describedhere because of the similarity of function between the liner nozzle 44and the sealing material nozzle 40.

After suficient quantity of the plastisol 38 has been deposited, avertically movable die support 50 moves a heated die 48 into theposition shown in FIG. 9. In this manner, the plastisol is formed withone surface thereof roughly parallel to the principal end panel 26, andthe other surface is strongly adhered to the tear-out portion 32 and tothe score line 34 and the ridge S2 defining same.

The distance between the inside surface of the tearout portion 32 andthe principal end panel 26 is about 0.010 to 0.020 inch in the preferredembodiment. The die 48 is suitably shaped to cover and overlap themarginal edges of the tear-out area 32 so as to wipe excess material 38from the depression within the tear-out area 32 after which the material38 may be hardened by conventional techniques. As pointed out above, afurther oven drying step may be utilized.

It is preferred that the depth or height of the ridge 52 is about 0.020to 0.050 inch, measured from the plane of the principal end panel 26.The function of this ridge 52 is not only to help define the tear-outarea 32 in the desired manner, but to provide protection for the canuser from any sharp edges which may remain when the tear-out portion 32is removed. A third function is to impart additional bending stiffnessin the area of the end surrounding the tear out portion, to minimize thelikelihood of accidental opening of the end by undue exing. In addition,such ridges or bosses provide a residue of extensible metal whichsimplifies forming the rivet 28.

The depth of the score line 34 is preferably such that the metalremaining underneath the score or cut is from about 0.0015 to 0.003 inchin thickness. Thus, in the case of an end made from so called 55 to 75pound metal (.006 to .0085 inch thick), the score line may be any- Wherefrom about 0.0045 to 0.0055 inch deep, depending on the temper, tensilestrength and other structural characteristics of the steel from whichthe end is formed.

Referring now to the materials used for making the inner seal, it ispreferred that a plastisol or like resinous material be used. Thus, inthe case of a vinyl plastic, such as polyvinyl chloride, the resin maybe in -a form of a plastisol, that is, a colloidal dispersion of theresin in a plasticizer; in the form of an organosol; or in the form of avinyl solution.

A typical plastisol material I have found suitable for use in thisinvention comprises a vinyl chloride resin, or vinyl chloride resincopolymerized with small amounts, say 5% or less, of vinyl acetateIand/or vinyl alcohol. These resins are insoluble in, but dispersablein, typical plasticizers, such as dioctyl phthalate, dioctyl sebacate,diphenyl phosphate, tricresyl phosphate and the like. After the resin isdispersed in the plasticizer, it may be cured, as by heating to 350 F.or more, whereupon solvation of the resinous component takes place, andthe resulting cured composition is in the form of a solvated plastic,that is, an organic glass, solid solution, or ultra-high viscosityfluid, being somewhat flexible, and having excellent adhesion to theprimers or inner coating materials commonly used on such ends. Suchtypical interior end coating lacquers or enamels include tung oil orlinseed oil based materials, epoxy phenolics, epoxy esters, vinylchlorides, modified vinyls or copolymerized epoxy phenolic typesynthetic resin coatings, selected with regard to product compatibilityand resistance, and adherence to subsequent or prior coating materials.

It has also been found that a vinyl or other suitable plastics, such asa urethane, an acrylic or an ester or amide type resin may be used inthe form of an organosol or, for example in a form of vinyl or otherplastic solution. Where a solution is used or where the external phaseof a dispersion has a low viscosity, the plastic material is more easilymetered and levelled in the desired position, such as that shown inFIGS. 8 and 9, but additoinal curing time may be required because suchmaterial is in a lower state of ou-re. Solvents and diluents may beappropriately selected as desired by those skilled in the art.

In suchcases, a longer curing time may be needed, but this is notcritical where a turret type machine or the like is used, whereinseveral seconds of curing time are available.

Likewise, complete cure of the resin is not necessary as long as theseal has enough stiffness to maintain its integrity and remain tack-freeduring subsequent handling operations.

It will be understood that the exact type of resin or the curingmechanism thereof is not important provided that the material adheresstrongly to the metal, and that it is inert with respect to the product.Preferably, its internal cohesive strength should be considerably lessthan the force of its adhesion to the metal substrate.

Likewise, for reasons of economics, it is desirable to confine the sealonly to the area covering the tear-out portion of the end and slightlyoverlapping the outer edges thereof, but it is not strictly necessarythat the tear-out portion 32 of the end 20 be offset from the principalend panel 26. If the panels 26-32 are coplanar, the die 48, instead ofbeing fiat on the bottom surface thereof, may have a recess of a shapecorresponding to that of a tearout area so as to form a seal ofgenerally uniform thickness in such an area. The construction andoperation of so called die liners of this type are well known in the canmaking art.

It is also possible to pre-form the seal from a vinyl plastisol, apolyethylene material, or the like, and fuse it in place with heat andpressure, but handling solid seal members is generally more difficultthan handling the seal member material in the liquid form.

The hollow integral rivet 28, shown, for example, in FIG. 4 hereof, ispreferred for use in the present invention, but a separate rivet may beused, as for example the types of rivets described in my co-peudingapplication Ser. No. 458,932, filed May 20, 1965. Likewise, the fingertab 30 may be attached by other known means if desired, such as by spotwelding, soldering, or the like.

Likewise, in the case of an extruded can, the rivet may -be integrallyformed with the end, but will have a solid shank portion.

It is not essential that the score yline 34 be on the inside surface ofthe can end but this construction is preferred for the reasons ofcorrosion resistance and the like set forth above.

As used herein, and in the claims the unmodified terms internally,externally, and upwardly, and the like, indicate these directions inposition of use of the finished can end when it is attached to the topof a container. Thus, upwardly and externally means the bottom surfacesof the ends as shown in FIGS. 5 through 9 inclusive, for example.

It will thus be seen, from the above description, and from the appendedclaims, taken in conjunction with the drawings, that the presentinvention provides a new and useful tear-out can end with an organicinner seal member having a number of novel advantages andcharacteristics, including those hereinbefore pointed out and otherswhich are inherent therein. I contemplate that certain changes andvariations may be made by those skilled in the art without departingfrom the spirit of the invention or the scope of the appended claims.

I claim:

1. An easy opening can end, including means on the outside peripheraledge thereof, adapted to be seamed to the end portion of a containerbody including:

(a) a principal end panel portion,

(b) a score line located in said end panel portion, and deiining atear-out portion adapted to be torn from said principal end portion,said tear-out portion having an area substantially less than one half ofthe area of said principal end portion,

(c) fastening means located inside said tear-out portion for attaching anger tab to said tear-out portion,

(d) a linger tab attached to said fastening means, and

(e) a seal member on the inner surface of said end panel, said innerseal member comprising a synthetic plastic resinous material, said sealmember completely covering said tear-out portion and having its outeredge portions extending slightly outwardly of said score line definingsaid tear-out portion.

2. An easy opening can end as defined in claim 1 in which said scoreline is on the inside surface of said can end.

3. An easy opening can end as dened in claim 1 in which said tear-outportion is in a plane which is parallel to, but offset from, the planeof said principal end portion, and extends somewhat outwardly therefromin position of use.

4. An easy opening can end as defined in claim 1 in which said fasteningmeans comprises a rivet with a hollow shank, integrally formed from thematerial comprising said can end.

5. An easy opening can end as dened in claim 1 in which said fasteningmeans comprises a rivet with a solid shank integrally formed from thematerial comprising said can end.

6. An easy opening can end as defined in claim 1 in which said sealmember comprises a vinyl plastisol ma-l terial.

7. An easy opening can end as defined in claim 1 which additionallyincludes a protective ridge closely adjacent and outside said scoreline, said ridge extending 8 axially outwardly of the said tear-outareain a normal position of use.

8. An easy opening can end as defined in claim 1 in which said seal hasa thickness of about .005 to .030 inch.

9. An easy opening can end as dened inclaim 1 in which said seal memberis substantially coplanarswith the inside surface of said principal endportion.

10. An easy opening can end as defined in claim 3 in which the amount ofsaid olsetA is from about 0.005 to about 0.030 inch. l

11. A method for making an easy opening can end, comprising, incombination,

(a) forming a can end,rincluding a principal end panel portion and angemeans adapted to be seamed to the end of` a container body,

(b) embossing a portion of said principal end portion 1 Ito form ashallow recessed area therein, said recessed area having a panelparallel to, but spaced apart, from the plane of said principal endportion,

(c) forming a score line in at least a portion of the recessed area thusformed, said score line defining a tear-out portion which is easilyseparable from the principal end panel portion of said end,

(d) attaching finger tab means to a part of said tearout portion, and

(e) completely covering and sealing said recessed area, including all ofsaid tear-out portion, with a resinous organic material, thereby formingan easy opening can end with an organic seal member on the inner surfacethereof.

12. A method as defined in claim 11 in which the method of covering andsealing said recessed area com prises depositing a liquid resinousmaterial in said recessed area to completely cover said tear-out portionof said end, and curing said resinous material to form a seal memberwhich is strongly adhered to the metal comprising said end.

13. A method for making an easy opening can end as defined in claim 11in which said score line is formed on the interior surface of saidrecessed area.

References Cited UNITED STATES PATENTS 2,870,935 l/ 1959 Houghtelling220-5 3 THERON E. CONDON, Primary Examiner.

GEORGE T. HALL, Assistant Examiner.

